As mobile devices are miniaturized and become multi-functioned, components for communication functions, camera functions, and audio reproduction functions are being modularized and remarkably miniaturized. Markedly, mobile devices such as mobile phones and PDAs include a camera function using a compact camera module (CCM).
A CCM includes an image sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The CCM converts light energy into an electric signal using the image sensor to obtain image data. In addition, the image data can be transmitted to and stored in a corresponding device.
FIG. 1 is a cross-sectional view illustrating a conventional camera module 10.
Referring to FIG. 1, the camera module 10 includes a printed circuit board 20, an image sensor 30, a housing 40, and a lens barrel 50.
Passive elements and the like are mounted on the upper surface of the printed circuit board 20 using a surface mount technology (SMT).
The image sensor 30 is disposed on the upper surface of the printed circuit board 20. An epoxy (not shown) is spread to the upper surface of the printed circuit board 20, and then the image sensor 30 is attached on the epoxy. In addition, a plurality of electrode pads 34 of the image sensor 30 are connected to an electrode terminal 22 of the printed circuit board 20 using a wire 36.
In addition, the housing 40 is bonded to the edge of the upper surface of the printed circuit board 20. An epoxy 24 is spread to the edge of the upper surface of the printed circuit board 20, and then the housing 40 is attached on the epoxy 24. The epoxy 24 spread to the edge of the upper surface of the printed circuit board 20 is cured at a predetermined temperature to fix the housing 40.
Meanwhile, the lens barrel 50 including a glass filter 52 and a lens 54 is coupled to an upper portion of the housing 40. For example, a lens barrel thread 56 is formed in the outer surface of the lens barrel 50 and a housing thread 44 is formed in the inner surface 42 of the housing 40. The lens barrel 50 is coupled to the housing 40 using the threads 56 and 44.
In the camera module, a coupling defectiveness between the housing 40 and the printed circuit board 20 may occur according to the amount of the spread epoxy 24 for fixing the printed circuit board 20 to housing 40. For example, when the epoxy 24, which is a spot type epoxy, is spread on the upper surface of the printed circuit board 20, a portion of the housing 40 to which the epoxy 24 is not spread may have a gap. As light enters through the gap between the housing 40 and the printed circuit board 20, the picture quality obtained from the image sensor 30 may deteriorate.
When the epoxy 24 is excessively spread to the edge of the upper surface of the printed circuit board 20, a fixing defectiveness of the housing 40 occurs according to a curing temperature of the epoxy 24 having elasticity and viscosity.
In addition, when the epoxy 24 is excessively spread, the epoxy 24 may get out of the interface between the housing 40 and the printed circuit board 20 and invade the image sensor 30 to contaminate the photo detecting area 32.
In addition, the housing 40 fixed on the printed circuit board 20 may be tilted by viscosity variations of the epoxy 24, and thus the center of the lens 54 placed on the upper portion of the housing 40 is not aligned with the center of a pixel region of the image sensor 30. This results in a defective assembly of the camera module. The housing 40 is tilted to cause a shift in focus. The shift in focus is detected after the camera module is assembled. Therefore, the camera module should be disassembled and the assembly yield is decreased.